1. Field of the Invention
The present invention relates to a mass flow controller capable of increasing the flow rate by a factor of two without changing the size between joints of an existing mass flow controller, capable of accurately controlling the flow rate even if the diameter of a control valve is increased with increasing flow rate, capable of restraining the generation of particles to the utmost in opening or closing the control valve, and having sealing properties which are stable for a long time in a connecting boundary between members constituting the path of flow of fluid such as gas or liquid.
2. Description of the Prior Art
(A) In the field of the manufacture of semiconductors, particularly very large scale integrated circuits, the diameter of a wafer tends to be increased from four inches to six inches and further, to eight inches so as to increase production and reduce costs. Correspondingly, the flow rate of gas used for manufacturing the very large scale integrated circuits is increased. It is desired that the mass flow controller copes with this trend.